Monitoring lasting about 18 months showed that the star emitted helium-rich gas in the last years of its life; the data hint at a binary system and a new “window” for studying stellar deaths via radio
Astronomers have detected, for the first time, an unusual type of radio waves from an exploding star, a feat that provides a rare glimpse into the final years of a massive star's life before it ends in a dramatic supernova.
The study focuses on Ibn-type supernovae. These events occur when a massive star is torn apart after releasing large amounts of helium-rich material shortly before it dies.
Tracking radio signals over time
Using the VLA telescope, the team monitored faint radio emissions from the explosion for about 18 months. These signals revealed clear evidence of gas that the star had ejected just a few years before it was destroyed, details that cannot be seen with optical telescopes alone.
Raphael Bar-Way, the lead author of the study, said: "We were able to use radio observations to 'see' the last decade of the star's life before the explosion. It's like a time machine to those last few years, especially the last five when the star was losing mass intensely."
How escaping gas serves as a cosmic mirror
Beer-Way explained that stars in other galaxies are usually too faint and far away to be studied before they explode. But when a star sheds large amounts of material beforehand, that surrounding gas can act as a “mirror.” When the supernova’s shock waves collide with that material, they create powerful radio waves that reveal what the star was doing near the end of its life.
The team also found hints that the star was likely part of a binary system – two stars orbiting each other – and interactions with its companion may have caused the large mass loss shortly before the explosion.
"To lose that much mass as we've seen in just the last few years... you almost certainly need two stars that are gravitationally bound together," he explained.
Opening a new window into the death of stars
The radio observations not only confirm that intense mass ejections can occur shortly before a supernova. They also present a new way to study how stars die throughout the universe. Until now, scientists have relied primarily on visible light to infer this behavior. Radio data now provide another powerful tool for understanding these events.
Beer-Way said future studies will extend this approach to examining more supernovae. The goal is to determine how common these dramatic mass-loss events are and what they reveal about the life cycles of massive stars.
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